Counterfactual history – “what would have happened if?” – is currently receiving keen editorial interest and was, roughly ten years ago in Anglophone countries, the subject of vigorous debate, which concluded with a cautious consensus. Yet, far from any polemical uses, the reasons for which are explored here, closer examination suggests, as already identified by Max Weber, that it is also a more ordinary way of reasoning, particularly in social sciences. It is therefore not a question of whether the approach should be promoted or rejected, but rather of detecting, through interdisciplinary literature, the challenges, risks and propositions resulting from its explicitness. Three aspects are analyzed here: the relationship between history and fiction, the weight of determinism and causality, and the political implications of focus on futures that never happened. Based on the observation of tension brought to light by counterfactual analysis, the article then takes a detailed look at criticism of various common uses and proposes further approaches which seem more pertinent – some evident, others experimental – with a view to enriching the historian’s toolbox. Thus, in encouraging the rereading of sources, the rejection of teleology and the analysis of critical moments, as well as the development of more precise and discontinuous concepts of temporalities and the implementation of pedagogical and ludic exercises, the counterfactual approach enables the researcher in particular to comprehend the essential, yet subtle, issue of possible worlds in history.